EPI base ring

ABSTRACT

Embodiments described herein relate to a base ring assembly for use in a substrate processing chamber. In one embodiment, the base ring assembly comprises a ring body sized to be received within an inner circumference of the substrate processing chamber, the ring body comprising a loading port for passage of the substrate, a gas inlet, and a gas outlet, wherein the gas inlet and the gas outlet are disposed at opposing ends of the ring body, and an upper ring configured to dispose on a top surface of the ring body, and a lower ring configured to dispose on a bottom surface of the ring body, wherein the upper ring, the lower ring, and the ring body, once assembled, are generally concentric or coaxial.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 61/780,447, filed Mar. 13, 2013, and U.S. provisional patentapplication Ser. No. 61/781,960, filed Mar. 14, 2013, which are hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a base ringassembly for use in a substrate processing chamber.

2. Description of the Related Art

Semiconductor substrates are processed for a wide variety ofapplications, including the fabrication of integrated devices andmicrodevices. One method of processing substrates includes depositing amaterial, such as a dielectric material or a conductive metal, on anupper surface of the substrate. For example, epitaxy is a depositionprocess that grows a thin, ultra-pure layer, usually of silicon orgermanium on a surface of a substrate. The material may be deposited ina lateral flow chamber by flowing a process gas parallel to the surfaceof a substrate positioned on a support, and thermally decomposing theprocess gas to deposit a material from the gas onto the substratesurface.

The chamber design is essential for film quality in epitaxy growth whichuses a combination of precision gas flow and accurate temperaturecontrol. Flow control, chamber volume, and chamber heating rely on thedesign of a base ring, which is typically disposed between a top domeand a lower dome (defining a processing volume for a substrate) anddictating the layouts of the process kit and inject/exhaust caps whichin turn influence the epitaxial deposition uniformity. Conventionalepitaxy chamber is very tall, resulting in there being a large distancebetween the top and bottom domes and the substrate. This results inhighly non-uniform flow, turbulence, eddy currents, and an overall largechamber volume. The chamber volume limits the ability of the system torun in transient, deposition-etch switching mode and requires longchamber stabilization time, which restricts process uniformity withsudden changes in cross sectional area over the substrate whichnegatively influences flow uniformity, induces turbulence, and affectsoverall uniformity of deposition gas concentration over the substrate.

Since flow characteristics directly impact the film performance on thesubstrate, there is a need for a deposition apparatus which provides abalanced and uniform flow field throughout the process chamber.

SUMMARY OF THE INVENTION

Embodiments described herein generally relate to a base ring assemblyfor use in a substrate processing chamber. In one embodiment, the basering assembly comprises a ring body sized to be received within an innercircumference of the substrate processing chamber, the ring bodycomprising a loading port for passage of the substrate, a gas inlet, anda gas outlet, wherein the gas inlet and the gas outlet are disposed atopposing ends of the ring body, and an upper ring configured to disposeon a top surface of the ring body, and a lower ring configured todispose on a bottom surface of the ring body, wherein the upper ring,the lower ring, and the ring body, once assembled, are generallyconcentric or coaxial.

In another embodiment, a process kit for a substrate processing chamberis disclosed. The process kit comprises a ring body sized to be receivedwithin an inner circumference of the substrate processing chamber, thering body comprising a loading port for passage of the substrate, a gasinlet, and a gas outlet, wherein the gas inlet and the gas outlet aredisposed at opposing ends of the ring body, and an upper ring configuredto dispose on a top surface of the ring body, and a lower ringconfigured to dispose on a bottom surface of the ring body, wherein theupper ring, the lower ring, and the ring body, once assembled, aregenerally concentric or coaxial.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1A is a schematic sectional view of a backside heating processchamber according to one embodiment of the invention.

FIG. 1B illustrates a schematic side view of the process chamber takenalong line 1B-1B in FIG. 1A.

FIG. 1C illustrates a perspective view of a substrate support havingthree support arms and three dummy arms design.

FIG. 2A illustrates a cross-sectional view of an upper dome according toone embodiment of the invention.

FIG. 2B illustrates a top view of the upper dome shown in FIG. 2A.

FIG. 2C is an enlarged view of a bonded joint illustrating the filletradius.

FIG. 3A illustrates a partial perspective cross-sectional view of a gasinlet mechanism that may be used in the process chamber of FIG. 1Aaccording to one embodiment of the invention.

FIG. 3B illustrates secondary inlet of the first inlet channel beingconfigured at an angle (a) with respect to a vertical passage of thefirst inlet channel.

FIG. 3C illustrates a first inlet channel and a second inlet channel arein fluid communication with a process gas supply source.

FIG. 4A illustrates a perspective view of a clamp ring that may be usedin place of the clamp ring of FIG. 1A according to one embodiment of theinvention.

FIG. 4B illustrates openings in a lower surface communicating with adistribution plenum formed through the clamp ring.

FIGS. 5A and 5B are schematic illustrations of the one or more lampassemblies including one or more flexible standoffs, according to oneembodiment.

FIG. 6 illustrates a perspective view of a liner assembly that can beused in place of the liner assembly of FIG. 1 according to oneembodiment of the invention.

FIGS. 7A and 7B are schematic illustrations of a lower dome that may beused in place of the lower dome of FIG. 1A according to one embodimentof the invention.

FIG. 7C is an enlarged view of a bonded joint illustrating the filletradius.

FIG. 8A shows a perspective cross-sectional view of an exemplary basering that may be used in replace of the base ring of FIGS. 1A and 1B.

FIG. 8B is a perspective view of the base ring of FIG. 8A from anotherangle showing an upper ring and a lower ring according to one embodimentof the invention.

FIG. 8C is an enlarged, partial cross-sectional view of the base ring ofFIG. 8B showing an upper trench and a lower trench formed in the topsurface and the bottom surface of the base ring, respectively, forreceiving the upper ring and the lower ring.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. In some instances, well-knownstructures and devices are shown in block diagram form, rather than indetail, in order to avoid obscuring the present invention. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be utilized and that logical, mechanical,electrical, and other changes may be made without departing from thescope of the present invention.

FIG. 1A illustrates a schematic sectional view of a backside heatingprocess chamber 100 according to one embodiment of the invention. FIG.1B illustrates a schematic side view of the process chamber 100 takenalong line 1B-1B in FIG. 1A. It is noted that the liner assembly 163 andthe circular shield 167 has been omitted for clarity. The processchamber 100 may be used to process one or more substrates, including thedeposition of a material on an upper surface of a substrate 108. Theprocess chamber 100 may include an array of radiant heating lamps 102for heating, among other components, a back side 104 of a substratesupport 106 disposed within the process chamber 100. In someembodiments, the array of radiant heating lamps may be disposed over theupper dome 128. The substrate support 106 may be a disk-like substratesupport 106 as shown, or may be a ring-like substrate support 107 withno central opening as shown in FIG. 1B, which supports the substratefrom the edge of the substrate to facilitate exposure of the substrateto the thermal radiation of the lamps 102.

Exemplary Substrate Support

In some embodiments, the substrate support 106 may be a multiple armdesign as shown in FIG. 1C. In the embodiment shown in FIG. 10, thesubstrate support 190 has three support arms 192 a, 192 c, and 192 e andthree dummy arms 192 b, 192 d, and 192 f, each of the support arms anddummy arms being extended outwardly and angularly spaced apart from eachother around the axis “G” that is extending through the central shaft194. Greater or fewer support arms or dummy arms are contemplated. Thecorner 196 of each of the dummy arms 192 b, 192 d and 192 f along alengthwise direction of the support arm may be chamfered for betteroptic. Each of the support arms and dummy arms 192 a-192 f may be at anangle “A” of about 5° to about 15° with respect to the axis “G”. In oneexample, the angle “A” is about 10°. The end of the support arms 192 a,192 c and 192 e may be bended upward to confine the substrate to preventit from lateral movement.

The dummy arms 192 b, 192 d and 192 f generally do not contact orotherwise support the substrate. Instead, the dummy arms are designed toprovide a better heat transfer balance or a more even distribution ofheat from the lamps 102, thereby facilitating accurate temperaturecontrol of a substrate during processing. During processing, thesubstrate support 190 absorbs thermal energy from lamps utilized to heata substrate support and/or substrate. The absorbed heat radiates fromthe substrate support 190. The radiated heat radiated by the substratesupport 190, particularly the support arms 192 a, 192 c, and 192 e, isabsorbed by the substrate support 190 and/or substrate. Because of therelatively close position of the support arms 192 a, 192 c, and 192 e tothe substrate support 190 or substrate, heat is easily radiated to thesubstrate support 190, causing areas of increased temperature adjacentto the support arms 192 a, 192 c, and 192 e. However, utilization of thedummy arms 192 b, 192 d and 192 f facilitates a more uniform radiationof heat from the support arms 192 a, 192 c, and 192 e to the substratesupport 190 and/or substrate, and thus, the occurrence of hot spots isreduced. For example, the utilization of dummy arms 192 b, 192 d and 192f results in a uniform radiation of a substrate support, rather thanthree local hot spots adjacent the support arms 192 a, 192 c, and 192 e.

Referring back to FIG. 1A, the substrate support 106 is located withinthe process chamber 100 between an upper dome 128 and a lower dome 114.The upper dome 128, the lower dome 114 and a base ring 136 that isdisposed between the upper dome 128 and lower dome 114 generally definean internal region of the process chamber 100. The substrate 108 (not toscale) can be brought into the process chamber 100 and positioned ontothe substrate support 106 through a loading port 103, which is obscuredby the substrate support 106 in FIG. 1A but can be seen in FIG. 1B.

The substrate support 106 is shown in an elevated processing position,but may be vertically traversed by an actuator (not shown) to a loadingposition below the processing position to allow lift pins 105 to contactthe lower dome 114, passing through holes in the substrate support 106and the central shaft 132, and raise the substrate 108 from thesubstrate support 106. A robot (not shown) may then enter the processchamber 100 to engage and remove the substrate 108 therefrom though theloading port 103. The substrate support 106 then may be actuated up tothe processing position to place the substrate 108, with its device side116 facing up, on a front side 110 of the substrate support 106.

The substrate support 106, while located in the processing position,divides the internal volume of the process chamber 100 into a processgas region 156 that is above the substrate, and a purge gas region 158below the substrate support 106. The substrate support 106 is rotatedduring processing by a central shaft 132 to minimize the effect ofthermal and process gas flow spatial anomalies within the processchamber 100 and thus facilitate uniform processing of the substrate 108.The substrate support 106 is supported by the central shaft 132, whichmoves the substrate 108 in an up and down direction 134 during loadingand unloading, and in some instances, processing of the substrate 108.The substrate support 106 may be formed from silicon carbide or graphitecoated with silicon carbide to absorb radiant energy from the lamps 102and conduct the radiant energy to the substrate 108.

In general, the central window portion of the upper dome 128 and thebottom of the lower dome 114 are formed from an optically transparentmaterial such as quartz. As will be discussed in more detail below withrespect to FIG. 2A, the thickness and the degree of curvature of theupper dome 128 may be configured in accordance with the presentinvention to provide a flatter geometry for uniform flow uniformity inthe process chamber.

One or more lamps, such as an array of lamps 102, can be disposedadjacent to and beneath the lower dome 114 in a specified, optimaldesired manner around the central shaft 132 to independently control thetemperature at various regions of the substrate 108 as the process gaspasses over, thereby facilitating the deposition of a material onto theupper surface of the substrate 108. While not discussed here in detail,the deposited material may include gallium arsenide, gallium nitride, oraluminum gallium nitride.

The lamps 102 may be configured to include bulbs 141 and be configuredto heat the substrate 108 to a temperature within a range of about 200degrees Celsius to about 1600 degrees Celsius. Each lamp 102 is coupledto a power distribution board (not shown) through which power issupplied to each lamp 102. The lamps 102 are positioned within alamphead 145 which may be cooled during or after processing by, forexample, a cooling fluid introduced into channels 149 located betweenthe lamps 102. The lamphead 145 conductively and radiatively cools thelower dome 104 due in part to the close proximity of the lamphead 145 tothe lower dome 104. The lamphead 145 may also cool the lamp walls andwalls of the reflectors (not shown) around the lamps. Alternatively, thelower dome 104 may be cooled by a convective approach known in theindustry. Depending upon the application, the lampheads 145 may or maynot be in contact with the lower dome 114. Further descriptions of thelampheads 145 are discussed below with respect to FIGS. 5A and 5B.

A circular shield 167 may be optionally disposed around the substratesupport 106 and surrounded by a liner assembly 163. The shield 167prevents or minimizes leakage of heat/light noise from the lamps 102 tothe device side 116 of the substrate 108 while providing a pre-heat zonefor the process gases. The shield 167 may be made from CVD SiC, sinteredgraphite coated with SiC, grown SiC, opaque quartz, coated quartz, orany similar, suitable material that is resistant to chemical breakdownby process and purging gases.

The liner assembly 163 is sized to be nested within or surrounded by aninner circumference of the base ring 136. The liner assembly 163 shieldsthe processing volume (i.e., the process gas region 156 and purge gasregion 158) from metallic walls of the process chamber 100. The metallicwalls may react with precursors and cause contamination in theprocessing volume. While the liner assembly 163 is shown as a singlebody, the liner assembly 163 may include one or more liners as will bediscussed below with respect to FIGS. 3A-3C and 6.

As a result of backside heating of the substrate 108 from the substratesupport 106, the use of an optical pyrometer 118 for temperaturemeasurements/control on the substrate support can be performed. Thistemperature measurement by the optical pyrometer 118 may also be done onsubstrate device side 116 having an unknown emissivity since heating thesubstrate front side 110 in this manner is emissivity independent. As aresult, the optical pyrometer 118 can only sense radiation from the hotsubstrate 108 that conducts from the substrate support 106, with minimalbackground radiation from the lamps 102 directly reaching the opticalpyrometer 118.

A reflector 122 may be optionally placed outside the upper dome 128 toreflect infrared light that is radiating off the substrate 108 back ontothe substrate 108. The reflector 122 may be secured to the upper dome128 using a clamp ring 130. Detail descriptions of the clamp ring 130are further discussed below with respect to FIGS. 4A and 4B. Thereflector 122 can be made of a metal such as aluminum or stainlesssteel. The efficiency of the reflection can be improved by coating areflector area with a highly reflective coating such as with gold. Thereflector 122 can have one or more machined channels 126 connected to acooling source (not shown). The channel 126 connects to a passage (notshown) formed on a side of the reflector 122. The passage is configuredto carry a flow of a fluid such as water and may run horizontally alongthe side of the reflector 122 in any desired pattern covering a portionor entire surface of the reflector 122 for cooling the reflector 122.

Process gas supplied from a process gas supply source 172 is introducedinto the process gas region 156 through a process gas inlet 174 formedin the sidewall of the base ring 136. The process gas inlet 174 isconfigured to direct the process gas in a generally radially inwarddirection. During the film formation process, the substrate support 106may be located in the processing position, which is adjacent to and atabout the same elevation as the process gas inlet 174, allowing theprocess gas to flow up and round along flow path 173 across the uppersurface of the substrate 108 in a laminar flow fashion. The process gasexits the process gas region 156 (along flow path 175) through a gasoutlet 178 located on the side of the process chamber 100 opposite theprocess gas inlet 174. Removal of the process gas through the gas outlet178 may be facilitated by a vacuum pump 180 coupled thereto. As theprocess gas inlet 174 and the gas outlet 178 are aligned to each otherand disposed approximately at the same elevation, it is believed thatsuch a parallel arrangement, when combing with a flatter upper dome 128(as will be discussed in detail below), will enable a generally planar,uniform gas flow across the substrate 108. Further radial uniformity maybe provided by the rotation of the substrate 108 through the substratesupport 106.

Exemplary Gas inlet with Angled Injection

In some embodiments, the process gas supply source 172 may be configuredto supply multiple types of process gases, for example, a group IIIprecursor gas and a group V precursor gas. The multiple process gasesmay be introduced into the process chamber 100 through the same processgas inlet 174, or through separate gas inlets. In cases where separategas inlets are desired, an alternative approach may be adapted toimprove the mixing of process gases in the process chamber. FIG. 3Aillustrates a partial perspective cross-sectional view of a gas inletmechanism 300 according to one embodiment of the invention that may beused in the process chamber of FIGS. 1A and 1B to provide one or morefluids, such as a process gas or a plasma of a gas, to the processingvolume (e.g., process gas region 156 and purge gas region 158). The gasinlet mechanism 300 may serve as an injector liner, such as the injectorliner 614 of the liner assembly 600 of FIG. 6, and may rest on or besupported by an inject insert liner assembly 330 that is in fluidcommunication with a process gas supply source 372, such as the processsupply source 172 of FIG. 1A. As can be better seen in FIG. 3C, theinject insert liner assembly 330 may include a first set of gas passage331 a and a second set of gas passage 331 b that are configured todeliver different process gases in a controlled manner.

In general, the gas inlet mechanism 300 is disposed at locations wherethe process gas(es) is to be introduced into the process chamber. Thegas inlet mechanism 300 includes a body 302 having a first inlet channel304 and a second inlet channel 306. The first inlet channel 304 and thesecond inlet channel 306 are in fluid communication with one or moreprocess gas supply sources 372. The body 302 generally goes around aportion of the inner circumference of the process chamber 100. The body302 includes a cylindrical inner diameter that is sized to be fitted inthe cut-outs of an upper liner and an exhaust liner (e.g., the upperliner 608 and the exhaust liner 612 of FIG. 6). Therefore, the body 302is removably combined with the exhaust liner and the upper liner of theliner assembly. Further details of the liner assembly are discussedbelow with respect to FIG. 6.

The first inlet channel 304 has a longitudinal axis that issubstantially orthogonal to the longitudinal axis of a first gas passage332, which is formed within the inject insert liner assembly 330. Afirst process gas may be flowed from the process gas supply source 372through the first set of gas passage 331 a into the first inlet channel304, which is in fluid communication with a first inlet 305. The firstinlet 305 is configured to provide the first process gas into theprocess chamber, for example, the process gas region 156 as shown inFIG. 1A. The gas inlet mechanism 300 may have one or more first inlets305, for example, about 3 to 20 first inlets, each connects torespective first inlet channel and gas passage to the process gas supplysource 372. Greater or fewer first inlets 305 are contemplated.

The first process gas may be a specific process gas or a mixture ofseveral process gases. Alternatively, one or more first inlets 305 mayprovide one or more process gases that are different than at least oneother first inlet, depending upon the application. In one embodiment,each first inlet 305 is configured at an angle “8” with respect to ahorizontal plane “P” that is generally parallel to a longitudinaldirection of a substrate 108, such that the first process gas, afterexisting the first inlet 305, is flowing at an angle along a firstdirection 307 as shown. In one example, the angle “θ” between alongitudinal direction of the first inlet 305 and the horizontal plane“P” is less than about 45°, such as about 5° to about 30°, for exampleabout 15°. In the example shown in FIG. 3B, the first inlet 305 isconfigured at an angle (α) with respect to the first inlet channel 304by about 25° to about 85°, for example about 45° to about 75°.

The second inlet channel 306 may be substantially similar in design tothe first inlet channel 304 in terms of the number of the gas inlets andprocess gas to be introduced. For example, the second inlet channel 306may be in fluid communication with one or more process gas supplysources 372. A second process gas, which may be a mixture of severalprocess gases, may be flowed from the process gas supply source 372through the second set of gas passage 331 b into the second inletchannel 306, which is in fluid communication with a second inlet 308.Alternatively, one or more second inlets 308 may provide one or moreprocess gases that are different than at least one other second inlet.The second inlet 308 is configured to provide the second process gasinto the process chamber, for example, the process gas region 156 asshown in FIG. 1A. Particularly, each second inlet 308 is configured toprovide the second process gas in a second direction 309 that isdifferent from the first direction 307 (see FIG. 3B) after existing thesecond inlet 308. The second direction 309 is generally parallel to thehorizontal plane “P” that is parallel to a longitudinal direction of thesubstrate.

Similarly, the gas inlet mechanism 300 may have one or more secondinlets 308, for example, about 3 to 20 second inlets, each connects torespective second inlet channel and gas passage to the process gassupply source 372. Greater or fewer second inlets 308 are contemplated.

It is contemplated that the flow rate, process gas composition and thelike at each first and second inlets 305, 308 may be independentlycontrolled. For example, in some examples some of the first inlets 305may be idle or pulsed during processing to achieve a desired flowinteraction with a second process gas that is provided by the secondinlets 308. In some cases where the first and second inlet channels 304,306 include only a single secondary inlet, the secondary inlet may bepulsed for similar reasoning as discussed above.

The first inlets 305 of the first inlet channel 304 and the secondinlets 308 of the second inlet channel 306 may be disposed verticallyoffset with respect to each other along the inner circumference of theprocess chamber. Alternatively, the first inlets 305 of the first inletchannel 304 and the second inlets 308 of the second inlet channel 306may be disposed in vertical alignment to one another. In either case,the first and second inlets 305, 308 are arranged such that the firstprocess gas from the first inlets 305 is properly mixed with the secondprocess gas from the second inlets 308. It is believed that mixing ofthe first and second process gases is also improved due to the angulardesign of the first inlet 305. The first inlets 305 of the first inletchannel 304 may be in a closer proximity to the second inlets 308 of thesecond inlet channel 306. However, it may be advantageous in certainembodiments to provide a proper distance between the first and secondinlets 305 and 308 to prevent the first process gas and the secondprocess gas from mixing together too early immediately after existingthe inlets.

The body 302 of the gas inlet mechanism 300 may have a reduced height tomatch with the near-flat configuration of the upper dome, as discussedbelow with respect to FIG. 2A. In one embodiment, the overall height ofthe body 302 may be between about 2 mm to about 30 mm, such as about 6mm to about 20 mm, for example about 10 mm. The height “H₁” on the sideof the body 302 facing the process gas region 156 may be of about 2 mmto about 30 mm, for example about 5 mm to about 20 mm. Since the heightof the body 302 is reduced, the height of the first inlet channel 304may be reduced accordingly to maintain the strength. In one example, theheight “H₂” of the first inlet channel 304 is about 1 mm to about 25 mm,for example about 6 mm to about 15 mm. Lowering the outer passage 310will result in a shallower angle of injection.

Referring back to FIG. 1A, purge gas may be supplied from a purge gassource 162 to the purge gas region 158 through an optional purge gasinlet 164 (or through the process gas inlet 174) formed in the sidewallof the base ring 136. The purge gas inlet 164 is disposed at anelevation below the process gas inlet 174. If the circular shield 167 ora pre-heat ring (not shown) is used, the circular shield or the pre-heatring may be disposed between the process gas inlet 174 and the purge gasinlet 164. In either case, the purge gas inlet 164 is configured todirect the purge gas in a generally radially inward direction. Duringthe film formation process, the substrate support 106 may be located ata position such that the purge gas flows down and round along flow path165 across back side 104 of the substrate support 106 in a laminar flowfashion. Without being bound by any particular theory, the flowing ofthe purge gas is believed to prevent or substantially avoid the flow ofthe process gas from entering into the purge gas region 158, or toreduce diffusion of the process gas entering the purge gas region 158(i.e., the region under the substrate support 106). The purge gas exitsthe purge gas region 158 (along flow path 166) and is exhausted out ofthe process chamber through the gas outlet 178, which is located on theside of the process chamber 100 opposite the purge gas inlet 164.

Similarly, during the purging process the substrate support 106 may belocated in an elevated position to allow the purge gas to flow laterallyacross the back side 104 of the substrate support 106. It should beappreciated by those of ordinary skill in the art that the process gasinlet, the purge gas inlet and the gas outlet are shown for illustrativepurpose, since the position, size, or number of gas inlets or outletetc. may be adjusted to further facilitate a uniform deposition ofmaterial on the substrate 108.

If desired, the purge gas inlet 164 may be configured to direct thepurge gas in an upward direction to confine process gases in the processgas region 156.

Exemplary Clamp Ring

FIG. 4A is a perspective view of a clamp ring 400 that may be used inplace of the clamp ring 130 of FIG. 1A according to one embodiment ofthe invention. The clamp ring 400 is disposed relatively above a basering (e.g., the base ring of FIGS. 1A-1B and 8A-8C) and is fastened tothe chamber 100 by fastening receptacles 402 disposed around the clampring 400. Fasteners (not shown) are disposed through the fasteningreceptacles 402 and into recesses in the sidewall of the process chamber100 to secure the clamp ring 400 to the process chamber 100.

The clamp ring 400 may provide with cooling features, such as coolingconduits 404. Cooling conduits 404 circulate a cooling fluid, such aswater, through and around the clamp ring 400. The cooling fluid isintroduced to the cooling conduits 404 through an inlet 408 andcirculates through the conduits 404 to emerge through an outlet 410. Thecooling conduits 404 may be connected by a ramp 406 that allows thecooling fluid to flow from one of the conduits 404 to the other conduit404.

In the embodiment of FIG. 4A, one conduit 404 is disposed around aninner portion of the clamp ring 400 while a second conduit 404 isdisposed around an outer portion of the clamp ring 400. Cooling fluid isintroduced to the conduit 404 disposed around the inner portion of theclamp ring 400 because the inner portion of the clamp ring 400 isexposed to the most heat, being nearest to the process conditions of thechamber 100. The cooling fluid absorbs heat from the inner portion ofthe clamp ring 400 most efficiently because the cooling fluid isintroduced at a relatively low temperature. When the cooling fluidreaches the conduit 404 disposed around the outer portion of the clampring 400, the cooling fluid has risen in temperature, but the coolingfluid still regulates the temperature of the outer portion of the clampring 400, which is heated less than the inner portion. In this way, thecooling fluid is flowed in a countercurrent fashion through the clampring 400.

The clamp ring 400 of FIG. 4A also has gas flow features provided tocool the upper dome 128. An inlet manifold 422 for a cooling gas appliescooling gas to the upper dome 128 of the chamber 100. A gas inlet 412communicates with an inlet plenum 414, which distributes the gas alongthe inlet plenum 414. Openings in a lower surface 416 (the openings arenot shown) communicate with a distribution plenum 418 formed through theclamp ring 400, which is shown in FIG. 4B.

FIG. 4B is a cross-sectional view of the lid portion of a processingchamber according to another embodiment. The lid portion includes theclamp ring 400. Gas flows into the distribution plenum 418 and into aninlet plenum 420 proximate to a periphery of the upper dome 128. Gasflows along an upper surface of the upper dome 128 regulating thetemperature of the upper dome 128.

Referring again to FIG. 4A, the gas flows into an exit manifold 424 thathas an outlet plenum 426 in communication with a collection plenum 428and a gas outlet 430. Regulating the thermal state of the upper dome 128prevents thermal stresses from exceeding tolerance and reducesdeposition on the lower surface of the upper dome 128. Reducingdeposition on the upper dome 128 maintains energy flux through the upperdome 128 to the reflector 122 and back through the upper dome 128 atnominal levels, minimizing temperature anomalies and non-uniformities inthe substrate 108 during processing.

Exemplary Lamphead Assembly

FIGS. 5A and 5B are schematic illustrations of the one or more lampassemblies 520 that may be used in place of the lamphead 145 of FIG. 1A,according to one embodiment of the invention. The lamp assemblies 520include one or more flexible standoffs 524. FIG. 5A illustrates across-sectional view of a lower dome 114 with a lamphead 545 and aprinted circuit board 552 according to one embodiment. As will bediscussed below, each of the lamp assemblies 520 can be attached to aflexible standoff 524, which may have a different height in accordancewith the angle of the lower dome 114 used. The lamp assembly 520, theflexible standoff 524 and the lamphead 545 are part of the lampheadassembly, alongside other components such as a reflector (not shown).FIG. 5B illustrates the one or more flexible standoffs 524 connected tothe one or more lamp assemblies 520 according to one embodiment. As willbe described below with respect to FIGS. 7A-7B, the lower dome 114 canbe formed in the shape of a generally circular, shallow martini glass orfunnel with a central opening 702. The lamp assembly 520 is disposedadjacent to and beneath the lower dome 114 in a specified, optimaldesired manner around the central shaft (e.g., the central shaft 132 ofFIG. 1A) to independently control the temperature at various regions ofthe substrate.

FIG. 5A depicts the lower dome 114, the PCB 552 and one or more lampassemblies 520, shown here as six lamp assemblies 520. It will be clearto one skilled in the art that certain elements have been left out ofthe description for sake of clarity. The PCB 552 can be any standardcircuit board designed to control the power distribution to the one ormore lamp assemblies 520. The PCB 552 can further comprise one or moreconnection slots 512, shown here as six connection slots, for connectionwith the one or more lamp assemblies 520. Though the PCB 552 is depictedhere as being flat, the PCB may be shaped according to the needs of theprocessing chamber. In one embodiment, the PCB board is positionedparallel to the lamphead 545.

Each of the one or more lamp assemblies 520 generally includes a lampbulb 522 and a lamp base 523. The lamp bulb 522 can be a lamp capable ofheating and maintaining the substrate at a specified temperature, suchas a halogen lamp, an infrared lamp and the like which are adapted asheating devices. The lamp assemblies 520 can be connected with one ormore flexible standoffs 524, described in more detail with reference inFIG. 5B.

The lower dome 114 can be comprised of a translucent material, such asquartz and can incorporate one or more elements described in thisdisclosure with reference to lower dome. The lower dome can be between 4and 6 mm thick. The lamphead 545 can be positioned under and in closeproximity to the lower dome 114. In one embodiment, the lamphead 545 isapproximately 1 mm from the lower dome 114.

The lamphead 545 has a plurality of fixed lamphead positions 504 whichassure a specific position and orientation of the lamp bulb 522. Thelamphead 545 can have as many as 400 or more fixed lamphead positions504. The fixed lamphead positions 504 can be in a multiple concentriccircle orientation. The fixed lamphead positions 504 can increase indepth as the holes extend from the inner radius to the outer radius. Thefixed lamphead positions 504 can be bored holes in the lamphead 545. Inone embodiment, the lamp bases 523 are held in a fixed orientation bythe lamphead 545 and cooled by the lamphead 545.

The lamp assemblies 520 and the connection slots 512 are shown as a setof six, this number is not intended to be limiting. There can be more orfewer of each, as is needed to maintain proper substrate temperature.Further, it is important to understand that this is a side view of athree dimensional structure. As such, though the components appear to bepositioned in a linear fashion, any position or combination of positionsis possible. For example, on a circular PCB 552, the lamps may bepositioned at a 3 cm interval on both the X and Y axis, thus filling thecircle. One skilled in the art will understand that there are numerousvariations of this embodiment.

FIG. 5B depicts the flexible standoff 524 according to one embodiment.The flexible standoff 524 shown here comprises a socket 526 and acontact adapter 528. The flexible standoffs 524, are depicted here ashaving a standard mill-max socket at socket 526 and an equivalentcontact adaptor at contact adapter 528, thus creating the lamp/standoffinterface and the standoff/PCB interface. However, this design choice isnot intended to be limiting. The socket design can be one of a number ofexisting designs or designs yet to be created which are capable oftransmitting power from a power source to the lamp 522. In oneembodiment, the flexible standoff is permanently attached to the PCB545, such as by soldering.

The flexible standoffs 524 can be composed of both conductive andnonconductive components such that the lamps receive power from thepower source. In one example, conductive metals, such as brass orcopper, is used to transmit power to the lamp 522 and the conductivemetal is surrounded by a nonconductive housing, such as a housing madeof plastic, flexible glass or ceramic fiber or beads. The flexiblestandoffs 524 can be of various lengths as appropriate for properradiance delivery to the lower dome 114. Since the flexible standoffs524 vary in length, the lamp assembly 520 can maintain the same generalsize and shape along the lower dome 114

Furthermore, the flexible standoffs 524 need not be straight. Theflexible standoffs 524 can take on curvature so that the lamp axis neednot be parallel to that of the processing chamber central axis. Statedanother way, the flexible standoffs 524 can allow the lamp axis to takeon a desired polar angle(s). The flexible standoffs 524 described hereincan be composed of a flexible material, such as a plastic with anelastomer.

The flexible standoffs 524 described herein can provide benefits in bothinterchangeability and orientation. The flexible standoffs 524, whenincorporating either a bent structure or a flexible material, may beconnected with a lamphead 545 with fixed lamphead positions 504 whichare not oriented perpendicular to the PCB 552. Further, the flexiblestandoffs 524 are designed to be non-consumable. When the lamp assembly520 fails, the lamp assembly 520 can be replaced by a single size oflamp assembly 520, thus making the lamp assembly 520 interchangeable inthe chamber, regardless of the position of the lamp assembly 520 on thePCB 552 or in the lamphead 545.

The flexible standoffs 524 provide proper positioning between the fixedlamphead positions 504, formed in the lamphead 545, and the connectionslots 512 formed in the PCB 552. The lamphead 545 can be composed of athermally conductive material, such as copper. In another embodiment,the lamphead 545 can be a copper conical section or an annulus ofrevolution which has an inner radius which bring the lamphead 545 inclose proximity to the central shaft 132 and an outer radius which isapproximately in line with the edge of the lower dome 114.

Formed over the PCB 552 can be one or more support structures, such as aspacer 514. The spacer 514, as shown in this example, can work inconjunction with the PCB 552 and the lamp assembly 520 to maintain aspecific direction of the lamp bulb 522, such as maintaining the lampassemblies 520 in a vertical direction. Further, the flexible standoff524 can have one or more structures which interact with the spacer 514,such as a lip 525. In this embodiment, the lip 525 ensures completeinsertion of the flexible standoff and maintains direction of both theflexible standoff 524 and the lamp bulb 522.

Exemplary Liner Assembly

FIG. 6 illustrates a perspective view of a liner assembly that can beused in place of the liner assembly 163 of FIG. 1A according to oneembodiment of the invention. The liner assembly 600 is configured forlining a processing region within a process chamber, such as theprocessing chamber of FIGS. 1A and 1B. The liner assembly 600 generallyprovides a gas inlet port 602, a gas outlet port 604, and a loading port606. The liner assembly 600 may work in conjunction with the base ringof FIGS. 8A-8C so that the position of the gas inlet port 602, gasoutlet port 604 and loading port 606 generally matches the process gasinlet 874, the gas outlet 878, and the loading port 803, respectively,at substantially the same elevation. Same level gas inlet/outlet enablesshorter flow path to the process chamber, enabling high conductanceexhaust and inject. Therefore, laminar gas flow and transitions are morecontrolled.

The liner assembly 600 may be nested within or surrounded by a base ring(e.g., the base ring of FIGS. 1A-1B and 8A-8C) disposed in the processchamber. The liner assembly 600 may be formed as an integral piece, ormay comprise multiple pieces that can be assembled together. In oneexample, the liner assembly 600 comprises multiple pieces (or liners)that are modular and are adapted to be replaced individually orcollectively to provide additional flexibility and cost savings due tothe modular design. Modular design of the liner assembly 600 enableseasy serviceability and increased functionality (i.e. changing ofdifferent injectors, such as the secondary inlets 305 shown in FIG. 3A).In one embodiment, the liner assembly 167 comprises at least an upperliner 608 and a lower liner 610 that are stacked vertically. An exhaustliner 612 may be combined by part of the upper liner 608 to improveposition stability.

The upper liner 608 and the exhaust liner 612 may be cut-out to receivean injector liner 614. The injector liner 614 generally corresponds tothe body 302 of FIG. 3A, and may include a gas inlet mechanism, such asthe gas inlet mechanism 300 discussed above with respect to FIG. 3A-3C.Each of the upper liner 608, the lower liner 610, the exhaust liner 612and the injector liner 614 includes a generally cylindrical outerdiameter that is sized to be nested within the base ring (not shown).Each of the liners 608, 610, 612, 614 may be supported by the base ringby gravity and/or interlocking devices (not shown), such as protrusionsand mating recesses formed in or on some of the liners 608, 610, 612.Interior surfaces 603 of the upper liner 608 and the lower liner 610 areexposed to the processing volume (e.g., the process gas region 156 andthe purge gas region 158).

In one embodiment, the upper liner 608 may be provided with a recessedfeature 616 to enable purging capability on the upper liner 608, therebypreventing unwanted deposition on the liner assembly while controllingthe temperature of the liner assembly.

Exemplary Upper Dome

FIGS. 2A and 2B are schematic illustrations of an upper dome 200 thatmay be used in place of the upper dome 128 of FIG. 1A according to oneembodiment of the invention. FIG. 2A illustrates a cross-sectional viewof the upper dome 200. FIG. 2B illustrates a top view of the upper dome200. As can be seen in FIG. 2B, the upper dome 200 has a substantialcircular shape and has a slightly convex outside surface 210 and aslightly concave inside surface 212 (FIG. 2A). As will be discussed inmore detail below, the convex outside surface 210 is sufficiently curvedto oppose the compressive force of the exterior atmosphere pressureagainst the reduced internal pressure in the process chamber duringsubstrate processing, while flat enough to promote the orderly flow ofthe process gas and the uniform deposition of the reactant material. Theupper dome 200 generally includes a central window portion 202 whichpasses the heat radiations, and a peripheral flange 204 for supportingthe central window portion 202. The central window portion 202 is shownas having a generally circular periphery. The peripheral flange 204engages the central window portion 202 around a circumference of thecentral window portion 202 along a support interface 206. In oneembodiment, the peripheral flange 204 is sealed within the side walls ofthe process chamber by an O-ring (labeled with 184 in FIG. 1A) disposedbetween the peripheral flange and the side walls, to provide seal forpreventing the processing gas within the process chamber from escapinginto the ambient environment. While not discussed here in detail, it iscontemplated that the lower dome may be similarly supported within theside walls of the process chamber using an O-ring (labeled with 182 inFIG. 1A). Fewer or more numbers of O-rings 182, 184 may be used.

The peripheral flange 204 may be made opaque or formed from clearquartz. The central window portion 202 of the upper dome 200 may beformed from a material such as clear quartz that is generally opticallytransparent to the direct radiations from the lamps without significantabsorption. Alternatively, the central window portion 202 may be formedfrom a material having narrow band filtering capability. However, someof the heat radiation re-radiated from the heated substrate and thesubstrate support may pass into the central window portion 202 withsignificant absorption by the central window portion 202. Thesere-radiations generate heat within the central window portion 202,producing thermal expansion forces. The peripheral flange 204, which maybe made opaque to protect the O-rings from being directly exposed to theheat radiation, remains relatively cooler than the central windowportion 202, thereby causing the central window portion 202 to bowoutward beyond the initial room temperature bow. The central windowportion 202 is made thin and has sufficient flexibility to accommodatethe bowing, while the peripheral flange 204 is thick and has sufficientrigidness to confine the central window portion 202. As a result, thethermal expansion within the central window portion 202 is expressed asthermal compensation bowing. The thermal compensation bowing of thecentral window portion 202 increases as the temperature of the processchamber increases.

The peripheral flange 204 and the central window portion 202 are securedat their opposite ends by a welded joint “B”. The peripheral flange 204is constructed with a fillet radius “r” along dimensional transitionportion 213 that is defined by the smooth and gradual change from thethinness of the central window portion 202 to the bulk of the peripheralflange 204. FIG. 2C shows an enlarged view of the bonded joint “B”illustrating the fillet radius of the peripheral flange 204. The filletradius is a continuously curved concave which may be considered as threecurves including the bottom of the inside of the peripheral flange 204,the main body of the transition portion 213, and the portion that mateswith the central window portion 202. Therefore, it may not be the sameradius throughout three curves. The fillet radius is typically measuredby determining the surface contour of the fillet radius and thenmathematically determining the best fit sphere to this contour. Theradius of this best fit sphere is the fillet radius.

The fillet radius eliminates sharp corners at the interface of the jointwhere the peripheral flange 204 and the central window portion 202 meet.The elimination of sharp corners also enables coatings to be depositedon the joints of the apparatus which are more uniform and thicker thanjoints having sharp corners. The fillet radius is selected to provide anincreased radial thickness of the peripheral flange 204 for better flowalong with the gradual variation and the “near-flat” curvature of thecentral window portion 202 (will be discussed below), resulting inreduced flow turbulence and better uniformity. Most importantly, thejoints with fillet radius also reduce or eliminate shearing forces atthe joints. In various embodiments, the fillet radius “r” of theperipheral flange ranges between about 0.1 inches and about 5 inches,such as between about 0.5 inches and about 2 inches. In one example, thefillet radius “r” is about 1 inch.

The peripheral flange 204 with a larger fillet radius is ideal handlingthermal and atmospheric stresses. As discussed previously, during theprocessing of the substrate, the upper dome 200 is loaded with a hightensile stress due to large pressure differential between the reducedinternal pressure within the process chamber and exterior atmosphericpressure acting on the upper dome. The high tensile stress can cause theupper dome to deform. However, it has been observed that the tensilestress of the upper dome 200 can be greatly reduced during the processif a lateral pressure “P” is inwardly applied to the side of theperipheral flange 204 (FIG. 2A). The lateral pressure applied onto theperipheral flange 204 forces the central window portion 202 to bowoutward and thus compensate the dome deformation. The lateral pressure“P” herein refers to a given amount of loading force in pounds persquare inch (psi) applied onto an outer peripheral surface 205 of theperipheral flange 204. In one embodiment, the lateral pressure “P” maybe about 200 psi or above. In another embodiment, the lateral pressure“P” may be between about 45 psi and about 150 psi. In one example, thelateral pressure “P” is about 80 psi to about 120 psi.

It has been also observed that the tensile stress of the peripheralflange 204 can be decreased from 1300 psi to 2000 psi without lateralpressure “P”, to below 1000 psi when a lateral pressure is applied tothe peripheral flange 204. Incorporating with the larger fillet radius“r” mentioned previously, the tensile stress of the peripheral flange204 can be greatly decreased when a lateral pressure “P” of about 80 psiis applied onto the peripheral flange 204. If the lateral pressure “P”is increased to about 150 psi, the tensile stress can be furtherreduced.

The thickness and outward curve of the central window portion 202 isselected to ensure that thermal compensation bowing is addressed. In theembodiment of FIG. 2A, the inner curve of the central window portion 202is shown as spherical, formed by a section of a sphere having a center“C” along the axis “A” and a large radius of curvature “R”. The centralwindow portion 202 may have a radius of curvature “R” of about 1122 mmplus or minus 300 mm to provide sufficient bow to withstand pressuredifferentials between zero and one atmosphere at substrate temperaturesbetween room temperature and processing temperatures of about 1200° C.or above. It is contemplated that the range of radius of curvature isintended to be for exemplary purpose only since it may vary dependingupon the upper dome angle (θ), diameter and thickness, peripheral flangethickness or width and the pressure differential acting on the surfaces210, 212 of the upper dome 200, etc. In various examples, the radius ofcurvature “R” may be about 900 mm to about 2500 mm.

Referring to FIG. 2A, in one embodiment the upper dome 200 isconstructed in a manner that the central window portion 202 is slopingwith respect to a horizontal plane “E” by an angle (θ). The horizontalplane “E” is generally parallel to a longitudinal direction of asubstrate (not shown, such as substrate 108 of FIG. 1A). In variousembodiments, the angle (θ) between the central window portion 202 andthe horizontal plane “E” is generally less than 22°. In one embodiment,the angle (θ) is about 6° to about 21°, such as about 8° to about 16°.In one example, the angle (θ) is about 10°. The central window portion202 sloped at about 10° provides an upper dome that is flatter than aconventional upper dome which typically has an angle (θ) of about 22° orgreater. The reduction of degree of angle (θ) will result in the upperdome 200 moving down about 0.05 inch to about 0.8 inch, for exampleabout 0.3 inch, as compared to the conventional upper dome.

The upper dome 200 may have a total outer diameter of about 200 mm toabout 500 mm, such as about 240 mm to about 330 mm, for example about295 mm. The central window portion 202 may have a thickness “T₁” ofabout 2 mm to about 10 mm, for example about 3 mm to about 6 mm. In oneexample, the central window portion 202 is about 4 mm in thickness. Thecentral window portion 202 may have an outer diameter “D₁” of about 130mm to about 250 mm, for example about 160 mm to about 210 mm. In oneexample, the central window portion 202 is about 190 mm in diameter. Theperipheral flange 204 may have a thickness “T₂” of about 25 mm to about125 mm, for example about 45 mm to about 90 mm. In one example, theperipheral flange 204 is about 70 mm in thickness. The peripheral flange204 may have a width “W₁” of about 5 mm to about 90 mm, for exampleabout 12 mm to about 60 mm, which may vary with radius. In one example,the peripheral flange 204 is about 30 mm in width. If the liner assemblyis not used in the process chamber, the width of the peripheral flange204 may be increased by about 50 mm to about 60 mm and the width of thecentral window portion 202 is decreased by the same amount. In such acase, the thickness of the peripheral flange 204 and the dome angle (θ)may be reduced accordingly and the amount of which can be calculated bythose skilled in the art based on the present specification.

If lower dome angles are adapted, the peripheral flange 204 may come inmore towards the central window portion 202. However, the limitingfactor on the central window portion 202 diameter is that the reflector(e.g., reflector 122 of FIG. 1) has to be able to reflect light back tothe area of the substrate plus the pre-heat ring (if used). Therefore,it would be advantageous to move the peripheral flange 204 inboardslightly while being able to provide a central window portion 202 havinga diameter of about 130 mm to about 300 mm.

The “near-flat” configuration of the upper dome 200, when combined witha base ring (such as the base ring 836 of FIG. 8A) and a flatter lowerdome (such as the lower dome 700 of FIGS. 7A and 7B), forms a shallow,spherical geometry which has been proved to be effective at withstandingpressure differentials between the inner and the exterior of the processchamber—especially when a reduced pressure or low pressure application,such as an epitaxial deposition process, is performed. In addition, ithas been observed that the “near-flat” configuration of the upper dome200, with the lateral pressure applied onto the peripheral flange 204,leads to lower shear stress in the region of welded joint “B” locatedbetween the peripheral flange 204 and the central window portion 202.While stressing of the central window portion 202 due to pressuredifferential can be addressed by using a thicker window portion, thickwindow portion can provide too much thermal mass, which leads to timelags for steady-state processing. Therefore, the overall throughput isreduced. Also, the upper dome with thick window portion exhibits poorelasticity during processing and causes high shear stress at theperipheral flange 204 while the central window portion 202 is beingradially contained by the peripheral flange 204. Furthermore, thickwindow portions take longer to dissipate heat which would affect thestabilization of the substrate. Since the spherical geometry inherentlyhandles reduced pressure effectively, the upper dome 200 can employquartz walls thinner than would be used by a conventional vessel withsudden large changes in cross sectional area above the substrate.

The thickness of the central window portion 202 of the upper dome 200 isselected at a range as discussed above to ensure that shear stressesdeveloped at the interface between the peripheral flange 204 and thecentral window portion 202 (FIG. 2C) is addressed. The thinner quartzwall (i.e., the central window portion 202) is a more efficient heattransfer medium so that less energy is absorbed by the quartz. The upperdome therefore remains relatively cooler. The thinner wall domes willalso stabilize in temperature faster and respond to convective coolingquicker since less energy is being stored and the conductive path to theoutside surface is shorter. Therefore, the temperature of the upper dome200 can be more closely held at a desired set point to provide betterthermal uniformity across the central window portion 202. In addition,while the central window portion 202 conducts radially to the peripheralflange 204, a thinner dome wall results in improved temperatureuniformity over the substrate. It may be advantageous to not excessivelyheat the peripheral flange 204 to protect the O-rings disposed aroundthe peripheral flange 204. It is also advantageous to not excessivelycool the central window portion 202 in the radial direction as thiswould result in unwanted temperature gradients which will reflect ontothe surface of the substrate being processed and cause film uniformityto suffer.

Table 1 below provides non-limiting particulars of the upper dome 200which is given as an illustrative example according to embodiments ofthe present invention.

TABLE 1 Degree angle (θ) (degree)  8-16 Central window portion thickness(mm)  2-10 Fillet radius (inches) 0.5-2  Outer diameter of centralwindow portion (mm) 130-250 Total outer diameter (mm) 240-360 Peripheralflange width (mm) 10-70 Peripheral flange thickness (mm)  25-125 Lateralpressure on peripheral flange (psi)  0-150 Exterior pressure on upperdome (Torr) 760   Chamber pressure (Torr) 0.1

By flattening out the upper dome 200, the radiation heat transfercharacteristics of the process chamber are vastly improved with lowerparasitic losses, less noise to the temperature sensors since thepyrometers can be positioned as close as possible to the substratesurface. The improved upper dome and the lower dome (as will bediscussed below with respect to FIGS. 7A-7C) also results in a reducedoverall chamber volume, which improves gas transition times and lowersthe pumping and venting times, resulting in lower cycle times andimproved substrate throughput. In addition, the “near-flat”configuration of the upper dome avoids or significantly minimizes gasflow turbulence or circulation in the upper processing region of thechamber as it avoids the problem associated with the prior design havingsudden change in cross sectional area above the substrate thatnegatively influences flow uniformity. Being near flat with increasedflange radius also facilitates the constant exhaust gas pressureuniformity across the chamber cross section, resulting in highly uniformflow fields over the substrate.

Exemplary Lower Dome

FIGS. 7A and 7B are schematic illustrations of a lower dome 700 that maybe used in place of the lower dome 114 of FIG. 1A according to oneembodiment of the invention. FIG. 7A illustrates a cross-sectional viewof the lower dome 700. FIG. 7B illustrates a top view of the lower dome700. As can be seen in FIG. 7A, the lower dome 700 is formed in theshape of a generally circular, shallow martini glass or funnel with acentral opening 708. The lower dome 700 is radially symmetrical about acenter axis “C” (FIG. 7B). The central opening 708, as discussedpreviously, provides free movement of a shaft (such as the central shaft132 of FIG. 1) therethrough during loading and unloading of a substrate.The lower dome 700 generally includes a stem portion 702, a peripheralflange 704, and a bottom 706 radially extended to connect the stemportion 702 and the peripheral flange 704. The peripheral flange 704 isconfigured to surround a circumference of the bottom 706. Alternatively,the peripheral flange 704 may at least partially surround the bottom706, depending upon the chamber design. The peripheral flange 704 andthe bottom 706, when combined with an upper dome and a base ring (suchas the upper dome 128 and base ring 136 of FIG. 1), generally define aninternal volume of the process chamber.

As will be discussed below, the bottom 706 is made thin and hassufficient flexibility to accommodate the bowing during the process,while the peripheral flange 704 is thick and has sufficient rigidness toconfine the bottom 706. The peripheral flange 704 may be made opaque toprotect the O-rings (labeled with 182 in FIG. 1) from being directlyexposed to the heat radiation. Alternatively, the peripheral flange 704may be formed from clear quartz. The bottom 706 of the lower dome 700may be formed from a material that is generally optically transparent tothe direct radiations from the lamps without significant absorption.

The peripheral flange 704 and the bottom 706 are secured at theiropposite ends by a welded joint “B”. The peripheral flange 704 isconstructed with a fillet radius “r” along dimensional transitionportion 713 that is defined by the smooth and gradual change from thethinness of the bottom 206 to the bulk of the peripheral flange 704.FIG. 7C shows an enlarged view of the bonded joint “B” illustrating thefillet radius of the peripheral flange 704. The fillet radius is acontinuously curved concave which may be considered as three curvesincluding the top of the peripheral flange 704, the main body of thetransition portion 713, and the portion that mates with the bottom 706.Therefore, it may not be the same radius throughout three curves. Thefillet radius is typically measured by determining the surface contourof the fillet radius and then mathematically determining the best fitsphere to this contour. The radius of this best fit sphere is the filletradius.

The fillet radius eliminates sharp corners at the interface of the jointwhere the peripheral flange 704 and the bottom 706 meet. The eliminationof sharp corners also enables coatings to be deposited on the joints ofthe apparatus which are more uniform and thicker than joints havingsharp corners. The fillet radius is selected to provide an increasedradial thickness of the peripheral flange 704 along with the gradualvariation and the “near-flat” configuration of the bottom 706 (will bediscussed below), providing a uniform radiation heat transfer to thesubstrate since the lamps can be placed closer to the substrate. Mostimportantly, the joints with fillet radius also reduce or eliminateshearing forces at the joints. In various embodiments, the fillet radius“r” of the peripheral flange 704 may range between about 0.1 inches andabout 5 inches, such as between about 0.5 inches and about 2 inches. Inone example, the fillet radius “r” is about 1 inch.

The peripheral flange 704 with a larger fillet radius is ideal handlingthermal and atmospheric stresses. During the processing of thesubstrate, the lower dome 700 is loaded with a high tensile stress dueto large pressure differential between the reduced internal pressurewithin the process chamber and exterior atmospheric pressure acting onthe lower dome. The high tensile stress can cause the lower dome todeform. However, it has been observed that the tensile stress of thelower dome can be greatly reduced during the process if a lateralpressure “P” is inwardly applied to the side of the peripheral flange704 (see FIG. 7A). The lateral pressure applied onto the peripheralflange 704 forces the bottom 706 to bow outward and thus compensate thedome deformation. The lateral pressure “P” herein refers to a givenamount of loading force in pounds per square inch (psi) applied onto anouter peripheral surface 726 of the peripheral flange 704. In oneembodiment, the lateral pressure “P” may be about 280 psi or above. Inanother embodiment, the lateral pressure “P” may be between about 60 psiand about 250 psi. In one example, the lateral pressure “P” is about 80psi.

It has been observed that the tensile stress of the peripheral flange704 can be decreased from 1300 psi to 2000 psi without lateral pressure“P”, to below 1000 psi when a lateral pressure is applied to theperipheral flange 704. Incorporating with the larger fillet radius “r”mentioned previously, the tensile stress of the peripheral flange 704can be greatly decreased when a lateral pressure “P” of about 80 psi isapplied onto the peripheral flange 704.

Referring to FIG. 7A, in one embodiment the lower dome 700 isconstructed in a manner that the bottom 706 is sloping with respect to ahorizontal plane “A” by an angle (θ). The horizontal plane “A” isgenerally parallel to a longitudinal direction of a substrate (notshown, such as substrate 108 of FIG. 1A). In various embodiments, theangle (θ) between the bottom 706 and the horizontal plane “A” isgenerally less than 22°. In one embodiment, the angle (θ) is about 6° toabout 21°, such as about 8° to about 16°. In another embodiment, theangle (θ) is about 6° to about 12°. In one example, the angle (θ) isabout 10°. The bottom 706 sloped at about 10° provides a lower dome 700that is flatter than a conventional lower dome which typically has anangle (θ) of about 22° or greater. The reduction of degree of angle (θ)will result in the lower dome 700 moving up about 0.3 inch to about 1inch, for example about 0.6 inch, as compared to the conventional lowerdome.

The thickness of the bottom 706 of the lower dome 700 is selected toensure that shear stresses developed at the interface between theperipheral flange 704 and the bottom 706 (FIG. 2C) is addressed. Invarious embodiments of the invention, the bottom 706 may have athickness “T₂” within a range from about 2 mm to about 16 mm, such asbetween about 3.5 mm and about 10 mm. In one example, the bottom 706 mayhave a thickness of about 6 mm. The bottom 706 may have an outerdiameter “D₂” of about 300 mm to about 600 mm, for example about 440 mm.The peripheral flange 704 may have a thickness “T₂” within a range fromabout 20 mm to about 50 mm, for example about 30 mm, and a width “W₂” ofabout 10 mm to about 90 mm, for example about 50 mm to about 75 mm,which may vary with radius. In one example, the lower dome 700 may havea total outer diameter of about 500 mm to about 800 mm, for exampleabout 600 mm. The central opening 708 may have an outer diameter ofabout 300 mm to about 500 mm, for example about 400 mm. In anotherembodiment, the central opening 708 may have an outer diameter of about10 mm to about 100 mm, for example about 20 mm to about 50 mm, such asabout 35 mm. It is contemplated that the size, angle (θ) and thethickness of the lower dome may vary, depending upon the chamber designand the pressure differential acting on the sides of the lower dome 700.

The “near-flat” configuration of the lower dome 700, when combined witha base ring (such as the base ring 836 of FIG. 8A) and a flatter upperdome (such as the upper dome 200 of FIG. 2A-2B), forms a shallow,spherical geometry which has been proved to be effective at withstandingpressure differentials between the inner and the exterior of the processchamber—especially when a reduced pressure or low pressure application,such as an epitaxial deposition process, is performed. In addition, ithas been observed that the “near-flat” configuration of the lower dome700, with the lateral pressure applied onto the peripheral flange 704,leads to lower shear stress in the region of welded joint “B” locatedbetween the peripheral flange 704 and the bottom 706. While stressing ofthe bottom 706 due to pressure differential can be addressed by using athicker dome wall (i.e., the bottom 706), thick dome wall can cause toomuch thermal mass, which leads to time lags for steady-state processing.Therefore, the overall throughput is reduced. Also, thick dome wallexhibits poor elasticity during processing and causes high shear stressat the peripheral flange 704 while the bottom 706 is being radiallycontained by the peripheral flange 704. Thick dome wall also takeslonger to dissipate heat which would affect the stabilization of thesubstrate. Since the spherical geometry inherently handles reducedpressure effectively, the lower dome 700 can employ a dome wall that isthinner than those conventional vessels having sudden large changes incross sectional area under the substrate.

Table 2 below provides non-limiting particulars of the lower dome 700which are given as an illustrative example according to embodiments ofthe present invention.

TABLE 2 Degree angle (θ) (degree)  6-16 Bottom thickness (mm) 3.5-10 Fillet radius (inches) 0.5-2  Outer diameter of bottom (mm) 300-600Total outer diameter (mm) 500-800 Peripheral flange width (mm) 50-75Peripheral flange thickness (mm) 25-50 Lateral pressure on peripheralflange (psi)  0-150 Exterior pressure on lower dome (Torr) 760   Chamberpressure (Torr) 0.1

By flattening out the lower dome 700 and the upper dome 200 as discussedabove, the processing volume of the process chamber is decreased, whichin turn reduces pumping and venting times. Therefore, the substratethroughput is improved. The improved lower dome also provides aconstant, uniform radiation heat transfer to the susceptor and thesubstrate because the radiant heating lamps can be placed as close tothe backside of the substrate as possible, resulting in bettertransmission, cleaner zonal uniformity on the backside of the susceptor(if a plate-like substrate support (FIG. 1A) were used), or the backsideof the substrate (if a ring-like substrate support (FIG. 1B) were used),thereby lowering parasitic losses since the radiant heating lamps can beconfigured as parallel as possible to the susceptor on which thesubstrate is placed. If desired, high resistance contact may beintroduced between quartz domes along flow path to mitigate cross-talk.

Exemplary Base Ring

FIG. 8A shows a perspective cross-sectional view of an exemplary basering that may be used in place of the base ring 136 as shown in FIGS. 1Aand 1B. The base ring 836 may be formed of aluminum or any suitablematerial such as stainless steel. The base ring 836 generally includes aloading port 803, a process gas inlet 874, and a gas outlet 878, andfunction in a similar way to the loading port 103, the process gas inlet174 and the gas outlet 178 shown in FIGS. 1A and 1B. The base ring 836comprises a ring body sized to be received within an inner circumferenceof the processing chamber of FIG. 1. The ring body may have a generallyoblong shape with the long side on the loading port 803 and the shortsides on the process gas inlet 874 and the gas outlet 878, respectively.The loading port 803, the process gas inlet 874 and the gas outlet 878may be angularly offset at about 90° with respect to each other. In oneexample, the loading port 803 is located on a side of the base ring 836between the process gas inlet 874 and the gas outlet 878, with theprocess gas inlet 874 and the gas outlet 878 disposed at opposing endsof the base ring 836. In various embodiments, the loading port 803, theprocess gas inlet 874 and the gas outlet 878 are aligned to each otherand disposed at substantially the same level as the loading port 103,the process gas inlet 174 and the gas outlet 178 of FIGS. 1A-1B.

The inner circumference 817 of the base ring 836 is configured toreceive a liner assembly, for example the liner assembly 163 of FIG. 1Aor the liner assembly 600 as discussed above with respect to FIG. 6. Theloading port 803, the process gas inlet 874, and the gas outlet 878 ofthe base ring 836 are configurable to work in conjunction with the linerassembly (FIG. 6) and the gas inlet mechanism (FIGS. 3A-3C), to provideone or more process/purge gases into the processing volume.

While not shown, fasteners may be disposed through fastening receptacles(not shown) formed on the top surface 814 of the base ring 836 and intorecesses (not shown) in a clamp ring (e.g., the clamp ring 130 of FIG.1A or clamp ring 400 of FIG. 4A) to secure the peripheral flange ofupper dome 128 between the base ring 836 and the clamp ring.

In one embodiment, the loading port 803 may have a height “H4” of about0.5 inches to about 2 inches, for example about 1.5 inches. The basering 136 may have a height “H3” of about 2 inches to about 6 inches, forexample about 4 inches. The height of the base ring 836 is designed suchthat the overall height of the base ring 836 is about 0.5 inch to about1 inch shorter than that of the conventional base ring height.Therefore, the distance between the substrate and an optical pyrometer(not shown, such as the optical pyrometer 118 of FIG. 1A) is alsoreduced. As a result, the reading resolution of the optical pyrometercan be greatly improved. In one example, the distance between thesubstrate and the optical pyrometer is about 250 mm. By reducing thedistance between the substrate and pyrometer as well as upper and lowerdomes, the radiation heat transfer characteristics of the processchamber are vastly improved with lower parasitic losses, less noise tothe temperature sensors, and more heat transfer with improvedcenter-to-edge uniformity from the radiant heating lamps to thesubstrate as well as the upper reflector to the substrate. The reducedheight of the base ring 836 and the “near-flat” configuration of theupper dome as discussed above with respect to FIGS. 2A-2B also enable arobust and accurate pyrometry at lower temperatures below 500° C. Theconfiguration of the process gas inlet 874 and gas outlet 878 enables aconcentric process kit (e.g., liner assembly) which greatly enhances inthe liner's ability to contain light leakage, allowing pyrometery to bemore accurate at temperatures below 500° C.

Since the base ring 836 is formed of a heat conductive material and iscloser to the radiant heating lamps due to the near-flat configurationof the lower dome, the base ring 836 may include one or more coolantchannels formed therein through which a cooling fluid, such as water, isflowed for cooling of the base ring. The coolant channels may bedisposed around the circumference of the base ring 836 in a regionproximity to an O-ring (e.g., O-rings 182, 184 of FIG. 1A). FIG. 8B is aperspective view of the base ring 836 of FIG. 8A from another angleshowing an upper ring 810 and a lower ring 812 according to oneembodiment of the invention. The upper ring 810 and the lower ring 812are configured to dispose on the top surface 814 and the bottom surface816 of the base ring 836, respectively. The upper ring 810 and the lowerring 812 have an annular shape and are generally concentric or coaxialonce they are assembled with the base ring 836.

FIG. 8C is an enlarged, partial cross-sectional view of the base ring836 of FIG. 8B showing an upper trench 818 and a lower trench 820 formedin the top surface 814 and the bottom surface 816 (FIG. 8B) of the basering 836, respectively, for receiving the upper ring 810 and the lowerring 812. The base ring 836 is schematically shown as two separate partsfor ease of understanding. The upper and lower trenches 818, 820 may beformed adjacent to an inner circumference 817 of the base ring 836. Theupper ring 810 may be formed in generally an “H” shape so that when itis rested within the upper trench 818, an annular fluid flow path isdefined between the upper ring 810 and the upper trench 818 and forms anupper coolant channel 822 for the base ring 836. Similarly, the lowerring 812 may be formed in generally an “H” shape so that when it isrested within the lower trench 820, an annular fluid flow path isdefined between the lower ring 812 and the lower trench 820 and forms alower coolant channel 824 for the base ring 836. The upper ring 810, thelower ring 812, and the base ring 836 may be welded together forming anintegrated body. The top and lower rings 810, 812 may be formed in anydesired shape as long as the cooling fluid is circulated throughrespective annular fluid flow path defined between the top and lowerrings 810, 812 and the base ring 836 for proper cooling of the base ring836.

In one embodiment, the base ring 836 may include a top interior wall 826extending upwardly from the top surface 814 of the base ring 836. Thetop interior wall 826 is configured around the inner circumference 817of the base ring 836 so that an outer portion 825 of the top interiorwall 826 and an inner portion 827 of the upper ring 810 defines a topannular trench 828, proximity to the upper trench 818, for placement ofan O-ring (not shown, e.g., O-rings 182, 184 of FIG. 1A). Similarly, thebase ring 836 may also include a bottom interior wall 830 extendingdownwardly from the bottom surface 816 of the base ring 836. The bottominterior wall 830 is configured around the inner circumference 817 ofthe base ring 836 so that an outer portion 829 of the bottom interiorwall 830 and an inner portion 831 of the lower ring 812 defines a bottomannular trench 832, proximity to the lower trench 820, for placement ofan O-ring (not shown, e.g., O-rings 182, 184 of FIG. 1A).

During process, cooling fluid is introduced from a cooling source (notshown) to the upper and lower coolant channels 822, 824 disposed aroundthe inner circumference 817 of the base ring 836 because the innercircumference 817 of the base ring 836 is exposed to the most heat,being nearest to the process conditions of the process chamber 100. Thecooling fluid absorbs heat from the inner circumference 817 of the basering 836 most efficiently because the cooling fluid is constantlyintroduced. The cooling fluid is flowed in a countercurrent fashionthrough the upper and lower coolant channels 822, 824 to help maintainthe base ring 836 and the O-rings at a relatively low temperature.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A base ring assembly for a substrate processing chamber, comprising: a ring body to be disposed within an inner circumference of the substrate processing chamber, the ring body comprising: a substrate loading port; a gas inlet; a gas outlet, wherein the gas inlet and the gas outlet are disposed at opposing ends of the ring body, and wherein the substrate loading port is angularly offset at about 90° with respect to the gas inlet and the gas outlet, and the substrate loading port, the gas inlet, and the gas outlet are at substantially the same level; an upper trench formed in a top surface of the ring body; and a lower trench formed in a bottom surface of the ring body; an upper ring disposed within the upper trench of the ring body, the upper ring and the upper trench define a first annular fluid flow path therebetween, wherein the ring body further comprises a top wall extending upwardly from the top surface of the ring body, the top wall is disposed around an inner circumference of the ring body; and an outer portion of the to wall and an inner portion of the upper ring defines a to annular trench for placement of an O-ring; and a lower ring disposed within the lower trench of the ring body, the lower ring and the lower trench define a second annular fluid flow path therebetween, wherein the ring body further comprises a bottom wall extending downwardly from the bottom surface of the ring body, the bottom wall is disposed around an inner circumference of the ring body; and an outer portion of the bottom wall and an inner portion of the lower ring defines a bottom annular trench for placement of an O-ring, and wherein the upper ring and the lower ring are individual pieces separated from the upper trench and the lower trench, respectively, and the upper ring, the lower ring, and the ring body, once assembled, are generally concentric or coaxial.
 2. The base ring assembly of claim 1, wherein the ring body is formed of aluminum or stainless steel.
 3. The base ring assembly of claim 1, wherein the substrate loading port, the gas inlet, and the gas outlet are disposed at substantially the same level.
 4. The base ring assembly of claim 1, wherein the ring body has a generally oblong shape with a long side on the substrate loading port and the short sides on the gas inlet and the gas outlet, respectively.
 5. The base ring assembly of claim 1, wherein the substrate loading port has a height of about 0.5 inches to about 2 inches.
 6. The base ring assembly of claim 1, wherein the ring body has a height of about 2 inches to about 6 inches.
 7. The base ring assembly of claim 1, wherein the upper ring and the lower ring have a general “H” shaped cross-section.
 8. The base ring assembly of claim 1, wherein the upper ring, the lower ring, and the ring body are welded together as an integrated body.
 9. A process kit for a substrate processing chamber, comprising: a ring body, comprising: a substrate loading port; a gas inlet; and a gas outlet, wherein the gas inlet and the gas outlet are disposed at opposing ends of the ring body, and the substrate loading port, gas inlet, and the gas outlet are disposed at substantially the same level; and an upper ring disposed on a top surface of the ring body, wherein the upper ring is shaped to define a first annular fluid flow path between the upper ring and the top surface of the ring body, wherein the ring body further comprises a to wall extending upwardly from the top surface of the ring body, the top wall is disposed around an inner circumference of the ring body; and an outer portion of the to wall and an inner portion of the upper ring defines a to annular trench for placement of an O-ring; and a lower ring disposed on a bottom surface of the ring body, wherein the lower ring is shaped to define a second annular fluid flow path between the lower ring and the bottom surface of the ring body, wherein the ring body further comprises a bottom wall extending downwardly from the bottom surface of the ring body, the bottom wall is disposed around an inner circumference of the ring body; and an outer portion of the bottom wall and an inner portion of the lower ring defines a bottom annular trench for placement of an O-ring, and wherein the upper ring and the lower ring are individual pieces separated from the ring body, and the upper ring, the lower ring, and the ring body, once assembled, are generally concentric or coaxial.
 10. A process chamber for processing a substrate, comprising: a rotatable substrate support disposed within the process chamber, the substrate support having a substrate support surface; a lower dome disposed relatively below the substrate support; an upper dome disposed relatively above the substrate support, the upper dome being opposed to the lower dome; and a ring body disposed between the upper dome and the lower dome, the ring body is disposed within an inner circumference of the process chamber, wherein the upper dome, the ring body, and the lower dome generally defining an internal volume of the process chamber, the ring body having: a substrate loading port; a gas inlet; a gas outlet, wherein the gas inlet and the gas outlet are disposed at opposing ends of the ring body; an upper trench formed in a top surface of the ring body; a lower trench formed in a bottom surface of the ring body; an upper ring disposed within the upper trench of the ring body, the upper ring and the upper trench define a first annular fluid path therebetween, wherein the ring body further comprises a top wall extending upwardly from the top surface of the ring body, the top wall is disposed around an inner circumference of the ring body; and an outer portion of the to wall and an inner portion of the upper ring defines a to annular trench for placement of an O-ring; and a lower ring disposed within the lower trench of the ring body, the lower ring and the lower trench define a second annular fluid path therebetween, wherein the ring body further comprises a bottom wall extending downwardly from the bottom surface of the ring body, the bottom wall is disposed around an inner circumference of the ring body; and an outer portion of the bottom wall and an inner portion of the lower ring defines a bottom annular trench for placement of an O-ring, and wherein the upper ring and the lower ring are individual pieces separated from the upper trench and the lower trench, respectively.
 11. The process chamber of claim 10, wherein the substrate loading port is angularly offset at about 90° with respect to the gas inlet and the gas outlet, and the substrate loading port, the gas inlet, and the gas outlet are at substantially the same level.
 12. The process chamber of claim 10, wherein the upper ring and the lower ring have a general “H” shaped cross-section.
 13. The process chamber of claim 10, wherein the upper dome comprises: a central window portion; and a peripheral flange engaging the central window portion at a circumference of the central window portion, wherein a tangent line on an inside surface of the central window portion that passes through an intersection of the central window portion and the peripheral flange is at an angle of about 8° to about 16° with respect to a planar upper surface of the peripheral flange.
 14. The process chamber of claim 10, wherein the lower dome comprises: a central opening; a peripheral flange; and a bottom extended radially outward to connect the peripheral flange and the central opening, wherein a tangent line on an outside surface of the bottom that passes through an intersection of the bottom and the peripheral flange of the lower dome is at an angle of about 8° to about 16° with respect to a planar bottom surface of the peripheral flange of the lower dome. 